Kooks puts over 50 years of race-winning experience into every header set they produce. These custom and available race series headers for popular GM model cars yield the largest horsepower gains of any header company to date. The flanges are laser cut 3/8” thick stainless steel to prevent warping with each port hand grinded to ensure they are perfectly smooth so there is no exhaust constriction. Every header collector has a Kooks scavenging spike in it to ensure maximum flow. With high quality T304 air craft quality stainless steel construction, these headers provide a long life of durability and reliability and carry a limited lifetime warranty. All gaskets, bolts and oxygen sensor extensions are included with your kit. !